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Countermeasures That Work

A Highway Safety Countermeasure Guide for State Highway Safety Offices

10th Edition, 2020


Purpose of the Guide

This guide is a basic reference to assist State Highway Safety Offices in selecting effective, science-based traffic safety countermeasures for major highway safety problems. The guide

  • describes major strategies and countermeasures relevant to SHSOs;
  • summarizes their use, effectiveness, costs, and implementation time; and
  • provides references to the most important research summaries and individual studies.

The guide is not intended to be a comprehensive list of countermeasures available for State use or a list of expectations for SHSO implementation. For a description of an optimal State countermeasure program, SHSOs should refer to the Highway Safety Program Guidelines, which delineate the principal components of each of the major program areas.

States should identify problem areas through systematic data collection and analysis and are encouraged to continue to apply innovation in developing appropriate countermeasures. The evaluations summarized in this guide allow SHSOs to benefit from the experience and knowledge gained by others and to select countermeasure strategies that have either proven to be effective or that have shown promise. States choosing to use innovative programs can contribute to the collective knowledge pool by carefully evaluating the effectiveness of their efforts and publishing the findings for the benefit of others.

How to Use the Guide

What’s included: The guide contains a topic chapter for each of 10 problem areas. Each chapter begins with a brief overview of the problem area’s size and characteristics, the main countermeasure strategies, a glossary of key terms, and a few general references. Next, a table lists specific countermeasures and summarizes their effectiveness, costs, use, and implementation time. Each countermeasure is then discussed in about a page.

The guide is an overview and starting point for readers to become familiar with the behavioral strategies and countermeasures in each program area. It includes countermeasures that have the most evidence of effectiveness as well as those used most regularly by SHSOs. Updates to the guide are based only on published research. Unpublished programs and efforts are not included in this edition.

Some countermeasure areas are covered in more depth than others due to availability of published research. For example, impaired driving has a long and rich research history while topics such as driver distraction and driver drowsiness have received less attention. This difference in the availability of published research findings is due to the relative scale of problem areas, availability of reliable data on frequency and characteristics of some safety problems, and the challenge of conducting scientifically valid studies in some behavioral areas.

References are provided for each countermeasure. When possible, summaries of available research are cited with web links where available, so users can find most of the evaluation information in one place. If no summaries are available, one or two key studies are cited. There has been no attempt to list all research, current studies, or program information available on any countermeasure. Readers interested in a problem area or specific countermeasure are urged to consult the references. Although all web links in this guide were accurate at the time of publication, please note that web links change periodically. For broken links to NHTSA documents, we recommend searching NHTSA’s behavioral safety research reports ( For broken links to other reports or documents, refer to the website for the agency that produced the report.

What’s not included: Since the guide is intended as a tool for SHSO use, it does not include countermeasures for which SHSOs have little or no authority or responsibility. For example, the guide does not include vehicle- or roadway-based solutions. Also, it does not include countermeasures that already are in place in every State, such as blood alcohol concentration laws. The guide does not include substantive details of specific countermeasures for emergency medical services or 911 services; these services are supported by traffic safety partners including State Offices of EMS. Finally, the guide does not include administrative or management topics such as traffic safety data systems and analyses, program planning and assessments, State and community task forces, or comprehensive community traffic safety programs.

What the effectiveness data mean: The effectiveness of countermeasures can vary immensely from State to State or community to community. What is done is often less important than how it is done. The best countermeasure may have little effect if it is not implemented vigorously, publicized extensively, and funded satisfactorily. Evaluation studies generally examine and report on high-quality implementation because there is little interest in evaluating poor implementation. Also, the fact that a countermeasure is being evaluated usually gets the attention of those implementing it, so that it is likely to be done well. The countermeasure effectiveness data presented in this guide probably show the maximum effect that can be realized with high-quality implementation. Many countermeasures have not been evaluated well or at all, as noted in the effectiveness data. Effectiveness ratings are based primarily on demonstrated reductions in crashes; however, changes in behavior and knowledge are taken into account in the ratings when crash information is not available.

NCHRP Guides: The National Cooperative Highway Research Program is developing a series of guides for State Departments of Transportation to use in implementing the American Association of State Highway and Transportation Officials Strategic Highway Safety Plan. This guide draws heavily on the published NCHRP guides and on several draft guides. It differs from the NCHRP guides because it is written for SHSOs, contains only behavioral countermeasures, and is considerably more concise. Readers are urged to consult the NCHRP guides relevant to their interests. They are available at

NCHRP has also developed a framework for estimating the costs and benefits associated with behavioral countermeasures. Each countermeasure included in Countermeasures That Work was reviewed and the potential savings of the countermeasures were projected. The subsequent report was designed to help States select countermeasures that will result in the greatest reduction in crashes, injuries, and fatalities, available at

Cochrane Reviews: Several chapters cite Cochrane Reviews. The Cochrane Collaboration is a nonprofit organization that produces and disseminates systematic reviews of the effects of healthcare interventions. The database of reviews is published quarterly as part of the Cochrane Library. More information about Cochrane Reviews can be found at

Disclaimers: As with any attempt to summarize a large amount of sometimes-conflicting information, this guide is highly subjective. All statements, judgments, omissions, and errors are solely the responsibility of the authors and do not necessarily represent the views of NHTSA. Users who disagree with any statement or who wish to add information or key references are invited to send their comments and suggestions for future editions (see bottom of page x for details).

New traffic safety programs and research appear almost weekly and sometimes daily. Websites change frequently. This means that this guide was out-of-date even before it was published. Readers interested in a specific problem area or countermeasure are urged to contact NHTSA for up-to-date information.

Preface to the Tenth Edition, 2020

This edition of Countermeasures That Work was prepared by Battelle Memorial Institute. Researchers who contributed to this edition include Christian M. Richard, Kelly Magee, Paige Bacon-Abdelmoteleb, and James L. Brown. The original Countermeasures That Work was prepared in 2005 by James H. Hedlund, Ph.D., of Highway Safety North, with the assistance of Barbara Harsha, executive director of the Governors Highway Safety Association. The chapters on pedestrian and bicycle safety were added in the Second Edition by William A. Leaf of Preusser Research Group. All chapters have been revised and updated for this edition. Information and research studies through May 31, 2016, have been reviewed and included as appropriate. Data has been updated to include information from 2015 FARS (Fatality Analysis Reporting System). A significant change in the 9th Edition is that the detailed descriptions of one- and two-star countermeasures were moved to appendices. The main part of the guide retains brief summaries for the one- and two-star countermeasures to facilitate navigation of the topics and to maintain continuity with previous editions.

Abbreviations, Acronyms, and Initialisms Used

  • AAA: was the American Automobile Association but now uses only the initials
  • AAAFTS: AAA Foundation for Traffic Safety
  • AAMVA: American Association of Motor Vehicle Administrators
  • AARP: was the American Association of Retired Persons but now uses only the initials
  • AASHTO: American Association of State Highway and Transportation Officials
  • ADTSEA: American Driver and Traffic Safety Education Association
  • ALR: administrative license revocation
  • ALS: administrative license suspension
  • AMA: American Medical Association
  • ASA: American Society on Aging
  • BAC: blood alcohol concentration, measured in grams per deciliter (g/dL)
  • BrAC: breath alcohol concentration, measured in grams per 210 liters of breath (g/210L)
  • CDC: Centers for Disease Control and Prevention
  • CIOT: NHTSA’s Click It or Ticket high-visibility seat belt enforcement campaign
  • CPS: child passenger safety
  • CPSC: Consumer Product Safety Commission
  • CTIA: Cellular Telecommunications and Internet Association
  • DOT: Department of Transportation (Federal or State)
  • DUID: driving under the influence of drugs
  • DWI: driving while impaired or intoxicated, and also often includes DUI, driving under the influence
  • DWS: driving while [driver’s license is] suspended
  • FHWA: Federal Highway Administration
  • FMCSA: Federal Motor Carrier Safety Administration
  • FMVSS: Federal Motor Vehicle Safety Standards
  • GDL: graduated driver licensing
  • GHSA: Governors Highway Safety Association
  • HVE: high-visibility enforcement
  • HOS: hours of service
  • IIHS: Insurance Institute for Highway Safety
  • IACP: International Association of Chiefs of Police
  • ITS: Intelligent Transportation Systems
  • LATCH: Lower Anchors and Tethers for Children
  • LEA: law enforcement agency
  • LEO: law enforcement officer
  • MAB: medical advisory board
  • MADD: Mothers Against Drunk Driving
  • MSF: Motorcycle Safety Foundation
  • NCHRP: National Cooperative Highway Research Program
  • NCSDR: National Center for Sleep Disorders Research
  • NCUTLO: National Committee on Uniform Traffic Laws and Ordinances [disbanded]
  • NHTSA: National Highway Traffic Safety Administration
  • NIAAA: National Institute on Alcohol Abuse and Alcoholism (a branch of NIH)
  • NIH: National Institutes of Health
  • NMSL: National Maximum Speed Limit
  • NCRUSS: The National Child Restraint Use Special Study. A NHTSA observational study of the use of car seats and booster seats for child passengers.
  • NSC: National Safety Council
  • NSF: National Sleep Foundation
  • NTSB: National Transportation Safety Board
  • PAS: passive alcohol sensor, a device to detect alcohol in the air near a driver’s face, used to estimate whether the driver has been drinking
  • PBT: preliminary breath test device, a small handheld alcohol sensor used to estimate or measure a driver’s BrAC
  • SFST: Standardized Field Sobriety Tests
  • SHSO: State Highway Safety Office
  • SMSA: National Association of State Motorcycle Safety Administrators
  • STEP: Selective Traffic Enforcement Program
  • THC: delta-9 tetrahydrocannabinol, the psychoactive constituent in cannabis. The THC metabolite, hydroxy-THC, is also psychoactive.
  • TIRF: Traffic Injury Research Foundation
  • TRB: Transportation Research Board
  • UVC: Uniform Vehicle Code

User Suggestions and Future Editions

NHTSA updates this guide biennially and may expand it with additional problem areas and countermeasures as appropriate. Users are invited to provide their suggestions and recommendations for the guide.

  • How can it be improved in form and content?
  • Specific comments on information in the guide.
  • Additional problem areas to include.
  • Additional countermeasures to include for the current problem areas.
  • Additional key references to include.

Please email your suggestions and recommendations to